继承AbstractAppender实现log4j的自定义标签，完成集群日志集中展示

我们很多机器是集群部署，如果单独去每台机器上面去找日志会很麻烦。另外很多生产上机器会对部分人员进行限制，但却需要他们去定位生产上的问题。这里通过继承AbstractAppender实现log4j的自定义标签来发送到同一服务器集中处理。

1、首先定义一个类继承AbstractAppender

/**
 * name 为log.xml里面配置标签
 * @author yin
 * @Method
 */
@Plugin(name = "LOG_SEND", category = "Core", elementType = "appender", printObject = true)
public class LogAppender extends AbstractAppender {

    protected LogAppender(String name, Filter filter, Layout<? extends Serializable> layout) {
        super(name, filter, layout);
    }

    /**
     *  加载类之前会调用的方法
     */
    @Override
    public void start() {
        //QueueUtil.execSys();
        super.start();
    }

    /**
     * 类结束之前调用方法
     */
    @Override
    public void stop() {
        super.stop();
    }


    /**
     * 日志输入的具体操作方式
     * @param logEvent
     */
    @Override
    public void append(LogEvent logEvent) {


        try {
            ThrowableProxy thrownProxy = logEvent.getThrownProxy();
            LogData logData;
            if (Objects.isNull(thrownProxy)) {
                logData= new LogData(logEvent.getMessage().getFormattedMessage(), logEvent.getThreadName(),
                        logEvent.getLevel().name(), logEvent.getTimeMillis(), logEvent.getLoggerName(),MachineIp.getIp());

            }else {
                StringBuilder sb = new StringBuilder(logEvent.getMessage().getFormattedMessage());
                sb.append("\n");
                dealErrorContent(thrownProxy, sb);
                for (ThrowableProxy throwableProxy = thrownProxy.getCauseProxy(); !Objects.isNull(throwableProxy); throwableProxy = thrownProxy.getCauseProxy()) {
                    sb.append("Caused by: ");
                    dealErrorContent(thrownProxy, sb);
                }
                logData= new LogData(sb.toString(), logEvent.getThreadName(),
                        logEvent.getLevel().name(), logEvent.getTimeMillis(), logEvent.getLoggerName(),MachineIp.getIp());

            }
            //System.out.println("========================================logData====" + logData);
            QueueUtil.getInstance().offer(logData);
        } catch (Exception e) {
            System.out.println("log4j httpAppender error !" + e);
        }

    }

    /**
     * 通过配置工厂来创建创建  LogAppender
     * @param filter
     * @param layout
     * @param name
     * @return
     */
    @PluginFactory
    public static LogAppender createLogAppender(@PluginElement("Filter") Filter filter, @PluginElement("layout") Layout<? extends Serializable> layout, @PluginAttribute("name") String name) {
        if (name == null) {
            LOGGER.error("No name provided for LogAppender");
            return null;
        }
        if (layout == null) {
            layout = PatternLayout.createDefaultLayout();
        }
        return new LogAppender(name, filter, layout);
    }

    private StringBuilder dealErrorContent(ThrowableProxy throwableProxy,StringBuilder sb ){
        sb.append(throwableProxy.getName());
        sb.app